The present invention relates to an apparatus and method useful for disinfecting a contact lens. More particularly, this invention relates to such an apparatus and method in which the presence of, and preferably the substantial absence of, an oxidative disinfectant is indicated.
Contact lenses should be periodically disinfected by the user to prevent infection or other deleterious effects on ocular health which may be associated with contact lens wear. Currently, there are several different conventional systems and methods which enable the user to disinfect his/her contact lenses between wearing times. These conventional cleaning and disinfection systems can be divided into "hot" and "cold" systems. Hot systems require the use of heat to disinfect the contact lenses, whereas cold systems use chemical disinfectants at ambient temperatures to disinfect the lenses.
Within the realm of cold disinfection systems are oxidative disinfectant, in particular hydrogen peroxide, disinfection systems. Disinfecting hydrogen peroxide solutions are effective to kill the bacteria and fungi which may contaminate contact lenses. However, residual hydrogen peroxide on a disinfected contact lens may cause irritation, burning or other trauma to the eye unless this hydrogen peroxide is destroyed, i.e., decomposed, neutralized, inactivated or chemically reduced. Therefore, destruction of the residual hydrogen peroxide in the liquid medium containing the disinfected contact lens is needed to enable safe and comfortable wear of the disinfected contact lens.
In order to avoid trauma to the eye caused by the presence of oxidative disinfectant on or in the lens, it would be advantageous to have an indication of the presence of such oxidative disinfectant. Additionally, it would be advantageous to have an indication of the substantial absence of such oxidative disinfectant, e.g., so that one would know it was safe to place the disinfected lens into one's eye.
A number of soluble color indicators have been suggested for use in contact lens disinfecting service. See, for example, Huth et al U.S. Pat. No. 4,670,178 and Davies et al U.S. Pat. No. 4,863,627. The use of soluble color indicators has certain disadvantages. For example, the soluble color indicator comes into intimate contact with the contact lens being treated and may have a detrimental effect on the lens and/or on the wearer of the lens. Also, such soluble color indicators are discarded with the disinfecting solution after each disinfection cycle. This "one time" use of color indicators increases the cost of this safety feature.
Color indication or indications of the presence and absence of hydrogen peroxide should be clear and distinct. Also, intimate contact between the lens being disinfected and the color indicator component should be avoided so that the lens and the lens wearer are not adversely affected by the color indicator component. Further, since contact lenses are repeatedly disinfected, the color indicator component should be such as to repeatedly provide the desired color indication or indications in a reliable and reproducible manner.
There continues to be a need for a contact lens care system which effectively disinfects a contact lens and provides an indication of the presence of the oxidative disinfectant so that the disinfected lens can be safely and comfortably worn.